1. Field
Exemplary embodiments relate to wireless communication, and more particularly, to a method and apparatus for controlling a timing of a Transmit Power Control (TPC) command considering Time Division Duplex (TDD)-Frequency Division Duplex (FDD) Carrier Aggregation (CA).
2. Discussion of the Background
A Transmission Power Control (TPC) refers to a technology to overcome the near-far problem caused when terminals are distributed near or far from a base station and perform signal transmission. When it is assumed that all the terminals transmit a signal with the same power, the intensity of a signal transmitted by a terminal located near the base station may be higher than that of a signal transmitted from a terminal located far from the base station. Therefore, the terminal located near the base station has no problem calling, but the terminal located far from the base station experiences a relatively strong interference. Therefore, the TPC refers to a technology that adjusts a transmission power of each terminal so that a base station receives a signal with power of a regular intensity. A base station may transmit a TPC command to a terminal for transmission power control. The TPC command may be applied to a predetermined subframe.
The wireless communication system may support Frequency Division Duplex (FDD) and Time Division Duplex (TDD). In the FDD, a carrier used for an uplink (UL) transmission and a carrier used for a downlink (DL) transmission exist, respectively, and both the UL transmission and the DL transmission are simultaneously executed in a cell. In the TDD, a UL transmission and a DL transmission are distinguished from each other, based on a time, in a single cell. In the TDD, an identical carrier may be used for a UL transmission and a DL transmission Thus, a base station and a UE repeatedly execute conversions between a transmission mode and a reception mode. The TDD includes a special subframe so as to provide a guard time for converting a mode between transmission and reception. The special subframe may include a Downlink Pilot Time Slot (DwPTS), a Guard Period (GP), and an Uplink Pilot Time Slot (UpPTS). For the TDD, through various UL-DL configurations, resources may be asymmetrically allocated for UL and DL transmissions.
Currently, frequency resources are scarce and various technologies are used in a part of the broad frequency bands. For this reason, to satisfy a higher data transmission rate requirement, as a scheme for securing a broadband bandwidth, each scattered band is designed to satisfy basic requirements for operating an independent system and a Carrier Aggregation (CA) has been employed, which binds up a plurality of bands as a single system. A band or a carrier that may independently operate may be defined as a Component Carrier (CC). Further, a TDD-FDD CA supports a CA of an FDD carrier and a TDD carrier.
In particular, when cross-carrier scheduling between a TDD carrier and an FDD carrier is configured for a terminal, a timing that is different from an existing scheduling timing and a Hybrid Automatic Repeat Request (HARQ)-Acknowledgement (ACK) timing may be applied to the terminal. Therefore, when the existing timing of a TPC command that was applied for a terminal that is connected with a FDD carrier or a TDD carrier, is applied, an uplink power control is erroneously indicated with respect to a subframe where a terminal does not execute uplink transmission, a power control based on an erroneous value may be indicated, or the like. To overcome the above described drawbacks, the present invention provides a new timing of a TPC command, considering TDD-FDD CA, and provides a PUSCH transmission power controlling method based on the same.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form any part of the prior art nor what the prior art may suggest to a person of ordinary skill in the art.